John Gill Commentary Acts 12:8

"And the angel said unto him, Gird thyself, and bind on thy sandals. And he did so. And he saith unto him, Cast thy garment about thee, and follow me." — Acts 12:8 (ASV)

And the angel said to him, gird yourself
He slept in his inner garment loose about him; therefore the angel bids him gird it up with his girdle, and prepare to walk out after him:

and bind on your sandals ;
which were a sort of shoes that covered only the soles of the feet, and were fastened to the leg, with strings:

and so he did ;
he did not ask any question, or the reason of these orders; he did not dispute the matter, but at once obeyed:

and he says to him, cast your garment about you ;
meaning his upper garment, or cloak, which lay by him:

and follow me ;
suggesting thereby, that he should take care of him, and show him his way, and bring him safe out of the prison.